feat : ajout des demi-journées d'absence dans le calendrier et l'export pdf

frontend/services/dto/absence.ts

@@ -1,10 +1,13 @@
 import type { Employee } from './employee'
 import type { AbsenceType } from './absence-type'
+import type { HalfDay } from './half-day'
 
 export type Absence = {
   id: number
   startDate: string
+  startHalf: HalfDay
   endDate: string
+  endHalf: HalfDay
   comment?: string | null
   employee: Employee
   type: AbsenceType